Driving force transmitter and valve timing controller using the same

ABSTRACT

A driving force transmitter includes a housing rotating with the driving shaft, a transmitting member rotating with the driving shaft; and a torsion coil spring having a first end engaged with the housing and a second end engaged with the transmitting member. The spring biases the transmitting member in an advance direction or a retard direction relative to the housing. The housing includes an opening confronting the transmitting member. The transmitting member includes a projecting portion rotatably supported by the opening. An intersection point of a rotational center axis of the transmitting member and a line passing through an engaging point of the first end of the biasing member and substantially vertically intersecting the rotational center axis is positioned in a range corresponding to a width in which the projecting portion is supported by the opening.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on Japanese Patent Applications No. 2005-121309 filed on Apr. 19, 2005, the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a driving force transmitter transmitting a driving force from a driving shaft to a driven shaft, and a valve timing controller for internal combustion engine provided with the driving force transmitter.

BACKGROUND OF THE INVENTION

JP-2004-300930A shows a valve timing controller which is provided in a driving force transmitting system in which a driving force is transmitted from a crankshaft of the internal combustion engine to a camshaft driving an intake valve and/or an exhaust valve. The valve timing controller adjusts the intake valve and/or the exhaust valve timing

As shown in FIG. 5, the valve timing controller includes a housing 300 rotating with the crankshaft, a vane rotor 200 rotating with a camshaft 900 and accommodated in the housing 300, and a coil spring 600 biasing the vane rotor 200 in an advance direction or a retard direction with respect to the housing 300. A space is formed between an inner surface of the housing 300 and the vane rotor 200. The space is divided into a plurality of chambers by the vane rotor 200. The chambers are filled with oil. A rotational phase between the housing 300 and the vane rotor 200 is adjusted by adjusting pressure in the chambers, whereby opening/closing timing of the intake valve and/or the exhaust valve is adjusted.

A through hole 330 is provided in the housing 300 to support a projecting portion 700 of the vane rotor 200. A torsion coil spring 600 is accommodated in the projecting portion 700. One end of the torsion coil spring 600 is engaged with a pin 800 (point “A”) provided on an outer surface of the housing 300, and the other end of the torsion coil spring 600 is engaged with a bottom surface of the projecting portion 700.

When a biasing force of the torsion coil spring 600 is applied to the housing 300 and the vane rotor 200, a force shown by an arrow “F1” is applied to the housing 300, so that a rotational moment “M” is generated in a direction that the housing 300 is tilted with respect to a rotational center axis of the vane rotor 200.

The rotational moment “M” tilts the housing 300 around a corner portion (point “B”), so that the inner surface of the housing 300 is press-fitted into an outer surface of the vane rotor 200. In this situation, when the rotational phase between the housing 300 and the vane rotor 200 is adjusted, it may be possible that a bonding is generated by a friction heat between the housing 300 and the vane rotor 200 at a place where both of them are press-fitted (an area “E” surrounded by a dashed line in FIG. 5). Since the housing 300 and the vane rotor 200 are made of aluminum alloy, the boding between them is easily generated.

SUMMARY OF THE INVENTION

The present invention is made in view of the foregoing matter and it is an object of the present invention to provide a driving force transmitter and a valve timing controller using the same, which is capable of restricting the boding therebetween even if a biasing force is applied to a housing and a vane rotor.

According to a start controller of the present invention, a driving force transmitter includes a housing rotating with the driving shaft, a transmitting member rotating with the driving shaft; and a torsion coil spring having a first end engaged with the housing and a second end engaged with the transmitting member. The spring biases the transmitting member in an advance direction or a retard direction relative to the housing. The housing includes an opening confronting the transmitting member. The transmitting member includes a projecting portion rotatably supported by the opening. An intersection point of a rotational center axis of the transmitting member and a line passing through an engaging point of the first end of the biasing member and substantially vertically intersecting the rotational center axis is positioned in a range corresponding to a width in which the projecting portion is supported by the opening.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings, in which like parts are designated by like reference number and in which:

FIG. 1 is a longitudinal section view of a valve timing controller for an internal combustion engine;

FIG. 2 is a transverse cross section view of the valve timing controller;

FIG. 3 is a front view of the valve timing controller;

FIG. 4 is a partially cross sectional side view for explaining force generated on the valve timing controller; and

FIG. 5 is a partially cross sectional side view for explaining force generated on a conventional valve timing controller.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described hereinafter with reference to the drawings.

A valve timing controller 10 includes a shoe housing 1 which is driven by a crankshaft (driving shaft) through a timing belt (not shown), and a vane rotor 2 (transmitting member) which is accommodated in the shoe housing 1 coaxially. The vane rotor 2 is made of aluminum alloy (for example, aluminum alloy including magnesium and silicon), and is driven by the shoe housing 1 to transmit torque to a camshaft 9 (driven shaft). At this moment, the vane rotor 2 rotates relative to the shoe housing 1 to rotate the camshaft 9 in an advance direction or a retard direction.

The shoe housing 1 includes a housing body 3, a sprocket wheel 4, and a plurality of bolts 11 which connect the housing body 3 and the sprocket 4 coaxially. The housing body 3 is made of aluminum alloy and includes an annular front plate 31 and a cylindrical body portion 32. The front plate 31 is provided with a cylinder portion 34 having a center opening 33. The cylinder portion 34 is projected from the front plate 31. The front plate 31 is provide with a pin-engaging hole 35

The body portion 32 includes four grooves 36 at an outer periphery thereof. The grooves 36 are provided at regular intervals. The body portion 32 includes four convex portions 37 at an inner periphery thereof. The convex portions 37 are respectively formed at positions corresponding to the grooves 36. The convex portions 37 are integrated with the front plate 31 and are provided with an internal thread hole 38 in an axial direction. As shown in FIG. 2, four concave portions 5 are formed between adjacent convex portions 37. Each convex portion 37 has a circular sliding surface 39 at a center side thereof. Each circular sliding surface 39 is arranged in such a manner as to be positioned in a single circle. A circular sliding surface 51 is respectively formed at the outer periphery of each concave portion 5. Each circular sliding surface 51 is arranged in such a manner as to be positioned in a single circle.

The sprocket wheel 4 has sprocket teeth 41 at the outer periphery thereof, and includes a sliding hole 42 on which the camshaft 9 slidably rotates. Through-holes 43 are formed between the sprocket teeth 41 and the sliding hole 42. A plurality of bolts 11 are engaged with the internal thread holes 38 through the through-holes 43 to fasten the housing body 3 and the sprocket wheel 4 together. The shoe housing 1 rotates in a clockwise direction in FIG. 2 in synchronization with the crankshaft through a timing chain (not shown) engaged with the sprocket wheel 4. The clockwise direction is referred to as an advance direction hereinafter.

The vane rotor 2 is connected with the camshaft 9 by means of a bolt 12. The vane rotor 2 is provided with four vanes 21 which divide four concave portions 5 into an advance chamber 5 a and a retard chamber 5 b respectively. The vane rotor 2 is capable of rotating in a predetermined angle range with respect to the shoe housing 1. When the advance chamber 5 a receives operating oil therein, the vane 21 is rotated in the advance direction. When the retard chamber 5 b receives the operating oil therein, the vane 21 is rotated in the retard direction.

The front plate 31, the body portion 32, the sprocket wheel 4, and the vane rotor 2 define the advance chamber 5 a and the retard chamber 5 b therein. These chambers 5 a, 5 b are fluidly sealed by means of the sliding surfaces 51, seal members 22, the sliding surfaces 39, and seal members 23.

The valve timing controller 10 has a differential pressure generating means (not shown) which supplies working fluid (oil) into the advance chamber 5 a and the retard chamber 5 b to generate a differential pressure therebetween. The differential pressure generating means includes an oil pump, a plurality of switching valves switching the oil pump between the advance chamber 5 a and the retard chamber 5 b, and an electromagnetic actuator driving the switching valves, and a controller controlling the actuator. The controller controls the differential pressure generating means in such a manner that the differential pressure is generated according to an engine driving condition, such as a crank angle, and engine speed, an accelerator position. This differential pressure makes a relative rotation between the vane rotor 2 and the shoe housing 1.

A stopper pin 24 is inserted to one of the vanes 21 in order to fix a preliminary position of the vane rotor 2 for starting the engine. The preliminary position is, for example, the most advance position. The stopper pin 24 is inserted in a through-hole 25 which penetrates the vane 21, and is biased rearward by means of a compressed coil spring 26. When the one end of the stopper pin 24 is engaged with a stopper hole 44 provided in the sprocket wheel 4, the position of the vane rotor 2 is locked with respect to the she housing 1.

The stopper pin 24 has a step portion 27 in order to move the stopper pin 24 forward. The step portion 27 communicates with the advance chamber 5 a. When the oil having a predetermined pressure is supplied to the advance chamber 5 a, the stopper pin 24 receives the pressure at the step portion 27, so that the stopper pin 24 moves to be disengaged with the stopper hole 44 against a biasing force of the compressed coil spring 26. The rear end of the stopper pin 24 communicates with the retard chamber 5 b. When the oil having a predetermined pressure is supplied to the retard chamber 5 b, the stopper pin 24 moves to be disengaged with the stopper hole 44 against the biasing force of the compressed coil spring 26.

As shown in FIGS. 1 to 3, a torsion coil spring (assist spring) 6 is provided between the shoe housing 1 and the vane rotor 2 to bias the vane rotor 2 in the advance direction. The assist spring 6 has a first elongated portion 61 and a second elongated portion 62 at both ends thereof respectively. The first elongated portion 61 is engaged with the show housing 1 or a member rotating with the shoe housing 1 together. The second elongated portion 62 is engaged with the vane rotor 2 or a member rotating with the vane rotor 2 together.

A bushing 7 is provided in a cylindrical concave portion 60 formed in a center portion of the vane rotor 2. The bushing 7 includes a circular cylinder portion 71 and a boss portion 72. The bushing 7 prevents the assist spring 6 from interfering with the housing body 3 or the vane rotor 2. The boss portion 72 has a bolt hole 73 through which the bolt 12 is inserted. The circular cylinder portion 71 substantially accommodates the assist spring 6. As shown in FIG. 1, an axial length of the cylinder portion 34 is the same as the axial length of the circular cylinder portion 71. The center opening 33 of the cylinder portion 34 supports an outer surface of the circular cylinder portion 71.

An engaging pin 8 is press-fitted into the pin-engaging hole 35. The first elongated portion 61 of the assist spring 6 is engaged with the engaging pin 8. The first elongated portion 61 passes through a clearance 63 provided in the circular cylinder portion 71. The circular cylinder portion 71 is provided with a spring-end groove 74 which corresponds to a relative rotational angel (about 90° in this embodiment) between the vane rotor 2 and the shoe housing 1. The cylinder portion 34 of the shoe housing 1 has a spring-end groove 40 of which shape is substantially the same as the spring-end groove 74. The second elongated portion 62 of the assist spring 6 is engaged with a radial groove 75 which is formed in the boss portion 72 of the bushing 7.

Referring to FIG. 4, a generating force on the housing body 3 in a case where the assist spring 6 biases the vane rotor 2 in the advance direction will be described. FIG. 4 is a partially cross sectional side view viewing FIG. 1 from above.

When the assist spring 6 biases the vane rotor 2 in the advance direction, a force “F1” is applied to a point “A” of the engaging pin 8 provided in the front plate 31. The point “A” corresponds to an engaging point. When the upward force “F1” is applied to the point “A”, an inner surface of the center opening 33 is press-fitted to the outer surface of the bushing 7 between a point “B” and a point “C”.

The positions of the points “A”, “B”, and “C” have a following relation. Intersecting points between the rotational center axis “D” of the vane rotor 2 and a plane including the points “A”, “B”, and “C” are referred to as points “A1”, “B1”, and “C1”. As shown in FIG. 4, the point “A1” is substantially consistent with the point “B1”, so that the rotational moment “M” is not generated or the rotational moment “M” is decreased unlike the conventional apparatus shown in FIG. 5. Thereby, the force biasing the inner surface of the front plate 31 into a side surface of the vane rotor 2 is disappeared or diminished to restrict the boding between the housing body 3 and the vane rotor 2 due to the friction heat in the area “E” shown by dashed line.

In the present embodiment, the point “A1” and the point “B1” are consistent with each other. At least when the point “A1” is positioned between the point “B1” and the point “C1”, the rotational moment “M” on the housing body 3 is not generated or is reduced. Thus, the bonding between the housing body 3 and the vane rotor 2 is restricted.

Since the first elongated portion 61 is engaged with a engaging pin 8 provided on the outer surface of the front plate 31, an additional function can be added between the housing body 3 and the vane rotor 2 other than a driving force transmitting function.

The rotational phase between the shoe housing 1 and the vane rotor 2 can be flexibly adjusted by controlling the hydraulic pressure in the chambers 5 a, 5 b. The valve timing of the intake valve and/or the exhaust valve can be suitably adjusted. 

1. A driving force transmitter transmitting a driving force from a driving shaft to a driven shaft, comprising: a housing rotating with the driving shaft or the driven shaft; a transmitting member accommodated in the housing, the transmitting member rotating with the driven shaft or the driving shaft; and a biasing member having a first end engaged with the housing and a second end engaged with the transmitting member, the biasing member biasing the transmitting member in an advance direction or a retard direction with respect to the housing; wherein the housing includes an opening confronting the transmitting member, the transmitting member includes a projecting portion rotatably supported by the opening, and an intersection point of a rotational center axis of the transmitting member and a line passing through an engaging point of the first end of the biasing member and substantially vertically intersecting the rotational center axis of the transmitting member is positioned in such a manner as to be within a range corresponding to a width in which the projecting portion is supported by the opening.
 2. A driving force transmitter according to claim 1, wherein the housing and the transmitting member are made of aluminum or aluminum alloy.
 3. A driving force transmitter according to claim 1, wherein the biasing member is a torsion coil spring accommodated in the projecting portion, the first end of the torsion coil spring is engaged with an outer surface of the housing, the second end of the torsion coil spring is engaged with a bottom surface of the projecting portion, the projecting portion projects by a specific projecting amount which is substantially the same as an axial length of the torsion coil spring, and an axial length of the inner surface of the opening is equal to or longer than the specific projecting amount.
 4. A driving force transmitter according to claim 3, wherein the housing is provided with a chamber accommodating the transmitting member, the transmitting member is provided with a projection which is accommodated in the chamber, rotates keeping a touch with an inner surface of the housing, and circumferentially divides the chamber, and a rotational phase between the housing and the transmitting member is adjusted by controlling pressure in the chamber.
 5. A valve timing controller for an internal combustion engine, comprising a housing rotating with a crankshaft of the engine or a camshaft driving an intake valve and/or an exhaust valve; a transmitting member accommodated in the housing, the transmitting member rotating with the crankshaft or the camshaft; and a torsion coil spring having a first end engaged with the housing and a second end engaged with the transmitting member, the torsion coil spring biasing the transmitting member in an advance direction or a retard direction with respect to the housing; wherein the housing includes an opening confronting the transmitting member, and a chamber accommodating the transmitting member, the transmitting member includes a projecting portion rotatably supported by the opening, and a projection which is accommodated in the chamber, rotates keeping a touch with an inner surface of the housing, and circumferentially divides the chamber, an intersection point of a rotational center axis of the transmitting member and a line passing through an engaging point of the first end of the biasing member and substantially vertically intersecting the rotational center axis of the transmitting member is positioned in such a manner as to be within a range corresponding to a width in which the projecting portion is supported by the opening, and a valve timing of the intake valve and/or the exhaust valve is adjusted by controlling pressure in the chamber. 